| 摘要 |
<p>The bath comprises copper ions, 1- hydroxyethylidene- 1,1 - diphosphonic acid, optionally together with either aminotri - (methylene phosphoric acid) or ethylene diamine tetro (methylene phosphonic acid) and a buffer (eg a carbonate) and has a pH of 6 to 10.5. The process involves providing an electrolyte having a pH of 6 to 10.5 and comprising copper ions, a complexing agent and a buffer and using as anodes a combination of a copper base soluble anode 16 and a nickel-iron alloy insoluble anode 18 containing from 10 to 40 weight % iron to provide a copper anode to nickel-iron alloy anode surface area ratio of from 1:2 to 4:1. The anode claimed comprises a nickel-iron alloy containing 10 to 40 weight % iron, 0.005 to 0.06 weight % sulphur, balance essentially nickel. <IMAGE></p> |
